After missing most of 2012 and all of 2013, Cory Luebke is perhaps further than ever from a return to the mound.

The Padres' talented left-hander will need a second reconstructive surgery on his throwing elbow after undergoing an MRI on Friday that showed a tear in the ulner collateral ligament. Luebke, 28, will miss his second consecutive season after his first Tommy John surgery on May 23, 2012.

"It's disappointing. I feel bad for him," Padres general Josh Byrnes said. "It's been a long road and we had some bumps in the fall, but he was sore two weeks ago. He came (to San Diego) last week and was still sore, so we took the MRI."

It had appeared that Luebke would begin this season in the bullpen and gradually ease his way back into rotation, a plan that may now have to wait until well into 2015. While Luebke had suffered a few setbacks in his rehabilitation -- 12 to 18 months for most Tommy John pitchers -- such halts are not atypical of the process.

In August, Luebke threw his first bullpen session since his surgery, only to be shut down in September because of pain. After being examined by orthopedic surgeon Dr. Tim Kremchek in Cincinnati, he resumed his rehabilitation and began throwing from a mound in November. By late December, the Padres felt Luebke had progressed far enough to at least be considered for Opening Day relief.

The results of Friday's scan erased that progress.

"We still have somewhat unanswered questions -- when did he tear it," Byrnes said. "The rehab as a whole hasn't gone smoothly, but for better or worse, we know now that he tore his UCL."

"We have a lot of depth," Byrnes said. "We finished the year with six starters and added Josh Johnson. I think having Cory return this year wasn't as much about quality as about depth. ... Obviously, the way Cory pitched before the injury was at a very high level."

Equipped with top-of-the-rotation ability, Luebke had been effective in both relief and, later, a starting role. In 2012, prior to going on the disabled list and subsequently having surgery, he went 3-1 with a 2.61 ERA in five starts. In 2011, he was 6-10 in 46 games (17 starts), posting a 3.29 ERA and prompting the Padres to sign him to a three-year, $12-million contract the following spring.

Luebke will make $3 million this season and $5.25 million in 2015. His deal includes a club option for 2016.

Johnson, a former All-Star acquired this offseason, is the first Padre to have undergone Tommy John surgery (2007). Two other San Diego starters, Casey Kelly and Joe Wieland, had their Tommy John operations in the year following Luebke's. Both are expected to return this season.

The most recent precedent for a major-league starting pitcher coming back from two Tommy John surgeries is Arizona's Daniel Hudson, who underwent his first in 2012. Last season, Hudson re-tore his ulner collateral ligament in a minor-league rehab start. Hudson, who was non-tendered by the Diamondbacks at the contract deadline, returned to the club on a minor-league contract. He will likely miss at least the first half of this season.

For Luebke, who had not made a minor-league rehab start in his recovery, there is of yet no expected return date. He last appeared in a game on April 27, 2012. That day, he won his third consecutive start, allowing two runs in six innings against the Giants.

In 55 career games, including 25 starts, Luebke is 10-12 with a 3.25 ERA. He has averaged more than a strikeout per inning.

"I think this second surgery is unusual and you can look at the odds for that," Byrnes said, "but first things first, he'll have surgery. We probably won't know a lot until after."